Search PubMed⌕ Search

Biomedical subjects

S Tamura

Publications and source records attributed to S Tamura.

At least 271 records · Page 15Linked to original sources
PubMed1997

Gadolinium-enhanced MR imaging of thyroid and parathyroid masses.

PURPOSE: To evaluate spin-echo and contrast material-enhanced dynamic magnetic resonance (MR) imaging in characterization of thyroid and parathyroid masses. MATERIALS AND METHODS: Conventional T1- and T2-weighted, gadolinium-enhanced dynamic, and gadolinium-enhanced T1-weighted spin-echo imaging sequences were performed in 85 patients with thyroid and parathyroid tumors. Findings from spin-echo imaging and dynamic curve patterns from mean signal intensity ratios were evaluated for each histologic tumor type. RESULTS: T1- and T2-weighted imaging did not enable differentiation of benign from malignant tumors. Primary thyroid lymphoma enhanced less than other solid thyroid tumors, and parathyroid adenoma also enhanced less than other tumors (P < .05 compared with papillary carcinoma. CONCLUSION: Gadolinium-enhanced MR imaging cannot enable prediction of histologic type in thyroid and parathyroid tumors. However, in cases of multiple tumors, the technique may improve the contrast between the different histologic types and sometimes suggest the diagnosis of primary thyroid lymphoma or parathyroid adenoma.

Adenoma↗
PubMed1997

High concentration of glucose increases mitogenic responsiveness to heparin-binding epidermal growth factor-like growth factor in rat vascular smooth muscle cells.

The effect of a high extracellular glucose concentration on the mitogenic response of rat vascular smooth muscle cells (SMCs) to heparin-binding epidermal growth factor-like growth factor (HB-EGF) was investigated. The mitogenic effect of HB-EGF was significantly greater in SMCs cultured in high glucose (25 mmol/L) than in cells cultured in low glucose (5.5 mmol/L) or at high osmolarity (5.5 mmol/L glucose plus 19.5 mmol/L mannitol). The mitogenic effect of epidermal growth factor (EGF), which shares the EGF receptor with HB-EGF, was not affected by glucose concentration. The mitogenic effect of HB-EGF was greater when incubated with heparan sulfate (HS) isolated from SMCs cultured in high glucose than with HS from cells cultured in low glucose. HS synthesized by cells in high glucose was of smaller molecular size and less sulfated than HS synthesized by cells in low glucose. The abundance of mRNA encoding HS-N-deacetylase/N-sulfotransferase (HS-NdAc/NST), a regulatory enzyme in the biosynthesis of HS, was decreased by high glucose in a protein kinase C-independent manner. These observations suggest that the enhanced mitogenic response to HB-EGF in SMCs cultured in high glucose may be attributable to changes in cell-associated HS. Downregulation of HS-NdAc/NST gene expression by high glucose may be related to the altered HS biosynthesis.

Animals↗
PubMed1997

Current status of conducting function tests in repeated dose toxicity studies in Japan.

It seems desirable to conduct as many function tests as possible in repeated dose toxicity studies, but is it practicable? The current status of conducting function tests in repeated dose toxicity studies in Japan was investigated by a literature survey of more than one thousand papers published in seven Japanese toxicology journals during the past 10 years and by a questionnaire survey directed to toxicologists among the Japan Pharmaceutical Manufacturers Association (JPMA) member companies. The function tests often carried out in repeated dose toxicity studies were, for example: 1) electro-retinography (ERG) and visually evoked potential (VEP) for visual test and tonometer for intraocular pressure; 2) auricular reflex, evoked response audiometry (ERA) and auditory brainstem response (ABR) to sound stimuli; 3) respiration and heart rate, electrocardiogram (ECG) and blood pressure by noninvasive cuff methods or using electronic devices such as telemetry; 4) body temperature, spontaneous motility and some adaptation tests (using rotarod and sloped plate in rats); 5) indocyanin (ICG) or bromosulfophtalein (BSP) for hepatic test; 6) phenolsulfonphtalein (PSP) and creatinine clearance for renal test; and 7) immunoglobulin, leukocyte phagocytosis, lymphocyte blastgenesis and natural killer cell (NK) for immuno-reaction test. Limitations to conducting function tests in repeated dose toxicity studies and issues to be resolved were discussed, based on questions and suggestions given by the respondents to the questionnaire. Although it certainly seemed desirable to conduct as many function tests as possible in repeated dose toxicity studies, most of the function tests so far introduced into toxicity studies were not satisfactory, because those tests could not be carried out under the restricted conditions of repeated dose toxicity studies, and not much reliable data from function tests were obtainable. A variety of function tests should firstly be incorporated into single dose toxicity studies together with development of a new concept for methodology in safety pharmacology.

Animals↗
PubMed1997

Occurrences of electroencephalographic (EEG) patterns that resemble epileptiform discharges in background EEG in epileptic patients.

The relationships of background EEG to epileptiform discharge development were studied in 9 epileptic patients having generalized spike and wave complexes (SWCs) with a maximum at the frontal location on either side. The instantaneous power spectrum of EEGs at F3, F4, C3, C4, P3, P4, O1, O2, T3 and T4 was estimated with wavelet transform. Subsequently, the similarity of power spectra between SWCs and background EEG was determined by use of Kullback-Leibler information and artificial neural network in each patient. Both similarity measures revealed that EEG patterns similar to SWCs occurred in the background activity just before SWCs at frontal locations. These findings suggested that these SWC-like EEG events occurred as poorly developed epileptiform discharges buried in the background activity.

Adolescent↗
PubMed1997

[Detection of human papilloma virus DNA and expression of p53 protein in patients with head and neck cancer].

We investigated the p53 expression and the presence of HPV DNA in 90 patients with squamous cell carcinomas (SCCs) of the head and neck and the relation to clinicopathological parameters and patients' prognosis. Immunohistochemical analysis of p53 protein was conducted by using monoclonal anti-p53 antibody, clone 1801 and clone 240. The relationship between the overexpression of p53 and the duration of survival of patients was analyzed. The polymerase chain reaction (PCR) was carried out with consensus primers capable of detecting HPV16, 18, 31, 33, 52b and 58. In situ hybridization was performed in the mesopharyngeal carcinoma to confirm the presence of HPV genomes in cancer cells with a wide-spectrum cDNA probe capable of detecting HPV6, 11, 16, 18, 30, 31, 33, 35, 45, 51, 52. Forty-five tissue samples (50%) were immunohistochemically positive for p53. T-category, N-category, primary site of tumor, clinical stage and tumor differentiation did not correlate with p53 expression. Our finding that p53 overexpression occurred in 50% of head and neck tumor samples is similar to the frequency of p53 overexpression reported for both lung and esophageal cancer. The common risk factor is the same in these neoplasms, and therefore it is not surprising to find a similar percentage of p53 overexpression. The prevalence of metastasis was higher in the patients with p53-positive staining than in those with p53-negative staining (p < 0.10). Analysis of cumulative survival rates of patients by the Kaplan-Meier method showed a close correlation between p53 expression and survival time. The survival differences according to p53 immunostaining were significant (p 0.05). Our results indicate that p53 immunohistochemical evaluation may be useful as one of the new prognostic parameters in head and neck cancer patients. The HPV genomes were detected in 9 of 90 patients (10.0%); 8 of 9 patients with mesopharyngeal cancer and one with maxillary cancer, namely, 29.6% of mesopharyngeal cancers and 6.7% of maxillary cancer contained HPV DNA sequences. Seven of 8 patients had SCCs of tonsil origin. Almost all of the HPV infections in our study occurred in patients with mesopharyngeal cancer, and it has been suggested that this anatomic subsite may be more frequently infected by HPV than other sites within the head and neck region. Among the 27 patients with mesopharyngeal cancer, HPV DNA-positive patients experienced a higher incidence of complete remission than HPV DNA-negative patients (87.5% vs. 26.3%, p < 0.05).

Aged↗
PubMed1997

[Localization of epileptogenic foci and visualization of propagating process in the seizure discharges using crosscorrelation analysis].

Electrocorticogram (ECoG) of intractable focal epilepsy was analyzed using AR model, wavelet analysis and crosscorrelation analysis. The sequential 3-dimensional visualization technique of phase shift maps was developed to localize the epileptic foci and to study their propagation process. The crosscorrelation of the epileptic discharges was calculated between the electrodes in every unit of time, to get the phase shift. More than two epileptogenic foci were localized and two kinds of propagating process were shown. These findings suggest that two kinds of mechanism might work in development of epileptic discharges, and our newly developed visualization technique is useful to investigate the epileptogenesis etiology.

Brain Mapping↗
PubMed1997

Coexpression of cytochrome P4502A6 and human NADPH-P450 oxidoreductase in the baculovirus system.

Heterologous expression using baculovirus vectors has become a popular method for the production of catalytically active cytochrome P450s (CYPs). We have systematically optimized the multiplicity of infection (MOI) for a coinfection approach for the coexpression of CYP2A6 (viral vector designated v2A6) and NADPH-P450 oxidoreductase (OR; viral vector designated vOR) using Sf9 insect cells. A 3000-fold range of MOI was examined in stationary culture and stirred suspension culture. Surprisingly, our results indicate that the best CYP2A6 catalytic activity (850-1300 pmol/ min/mg total lysate protein as measured by coumarin 7-hydroxylase activity) was obtained only when using a low MOI of v2A6 (1.5-3 x 10(-2)) and a vOR of 10- to 20-fold less. This activity was approximately 7- to 11-fold higher than the best activity obtained when infecting cells with v2A6 alone. At this level of coinfection, the P450 content ranged from 180 to 250 pmol/mg total lysate protein, and the NADPH cytochrome c reductase activity ranged from 350 to 520 nmol/min/mg total lysate protein. Increasing the MOI of both viruses to 50-fold higher resulted in lower overall activity with the optimum (250 pmol/min/mg total lysate protein) being seen earlier postinfection (60 vs. 72 hr). Increasing the MOI of vOR to levels comparable with those of v2A6, decreased coumarin 7-hydroxylase activity 14-fold. These results suggest that the best CYP2A6 catalytic activity depends on properly posttranslationally modified proteins accumulating in a right ratio as a result of primary, secondary, and possibly tertiary infection of both viruses. These results also suggest that high OR expression results in degradation of P450.

Animals↗
PubMed1997

Persistent sciatic artery aneurysm with ruptured internal iliac artery aneurysm.

A case of aneurysm of persistent sciatic artery with ruptured aneurysm of the internal iliac artery is reported. A 62-year-old man was admitted to our hospital in emergency because of abdominal severe pain. Abdominal CT and angiography showed aneurysm of the infrarenal aortic aorta and left internal iliac artery and left persistent sciatic artery. The persistent sciatic artery aneurysm was coursed down the left thigh. Left superficial femoral artery was supplying blood to the popliteal artery as normal connection. Emergency operation was performed. The left internal iliac aneurysm was ruptured to a retroperitoneal space. The aneurysm was replaced by a Y-shaped dacron double velour graft from the infrarenal abdominal aorta to right common iliac and left external iliac arteries, which was followed by a ligation at the origin of left persistent sciatic aneurysm. The pulsation of the left lower extremity was good and additional bypass procedure to the popliteal artery was not performed. The post-operative course of the patient was excellent and post-operative angiography showed normal anatomy of the left lower extremity. Optimal management of ruptured abdominal aneurysm thus requires not only an emergency operation but detailed observation of preoperative CT and angiography in order to scrutinize the associated vascular anomalies.

Aneurysm↗
PubMed1997

[Severe aortic regurgitation with marked thickening of the aortic annulus: a case report].

A 74-year-old woman with severe aortic regurgitation and marked thickening of the aortic annulus received aortic valve replacement. Transesophageal echocardiography demonstrated marked thickening of the aortic annulus. The maximum thickness of the aortic annulus was about 11 mm at the side of the right coronary cusp. Histological examination revealed non-specific inflammation of the aortic annulus and aortic valve chiefly composed of lymphocytes and plasma cells. Thickening of the aortic annulus associated with inflammatory aortitis was the cause of aortic regurgitation in this patient.

Aged↗
PubMed1997

A case of Turner's syndrome associated with partial anomalous pulmonary venous return complicated by dissecting aortic aneurysm and aortic regurgitation.

We report a successful surgical case with Turner's syndrome associated with partial anomalous pulmonary venous return (PAPVR) complicated by aortic dissection and aortic regurgitation without coarctation of the aorta. The patient, a 30-year-old woman, is of a short stature who was diagnosed with Turner's syndrome at the age of 12. She has suffered from dyspnea and edema of the legs since a year ago and was admitted to our hospital in June 1994 as echocardiography revealed rapid dilatation of ascending aorta and aortic regurgitation. A chest X-ray showed cardiothoracic ratio of 63% and transesophageal echocardiogram revealed that ascending aortic diameter was extended up to 60 mm at its maximum and that it was possible to distinguish true lumen from false lumen. The aortic arch was found to be normal. Also revealed by cardiac catheterization was drainage of the left upper pulmonary vein to the innominate vein. The L-R shunt ratio was 2.2. The surgery was performed by the Bentall method. The composite graft with a 21 mm St. Jude Medical prosthetic heart valve placed on the annulus of aortic valve. The ostiums of the coronary arteries were directly anastomosed to the composite graft with Carrel patch. After declamp of the aorta, the left pulmonary vein was directly anastomosed to the left atrial appendage without causing stenosis. The postoperative course was uneventful, and the cineangiogram after surgery demonstrated successful repair. Reports of cases of Turner's syndrome like this are sparse.

Abnormalities, Multiple↗
PubMed1997

[Evaluation of primary lung cancer and mediastinal lymph node metastasis using 99mTc-MIBI: comparison with 201T1 and relation to chemotherapeutic effect].

We compared the detectability of 99mTc-MIBI and 201T1-chloride for primary lung cancer and mediastinal lymph node metastasis. We also analyzed the relationship between 99mTc-MIBI uptake and effectiveness of chemotherapy in patients with small cell lung cancer. The subjects were fourty-six primary lesions and 8 mediastinal metastatic lymph nodes confirmed by operation, and dual-isotope SPECT technique was performed at both 20 min and 180 min after tracer injection. A tumor to normal lung ratio on both early (ER) and delayed image (DR) and retention index (RI) were calculated. The positive rates of 99mTc-MIBI (early; 82.6%, delayed; 54.3%) were comparable to 201T1 in most primary tumor (87.0% and 84.8%). Whereas tumor smaller than 3 cm diameter was poorly visualized on both 99mTc-MIBI (25% and 0%) and 201T1 (37.5% and 37.5%). Detectabilities of metastatic mediastinal lymph nodes of 99mTc-MIBI (62.5% and 25.0%) was comparable to those of 201T1 (62.5% and 50.0%). Regarding effectiveness of chemotherapy, NC group showed lower uptake of 99mTc-MIBI and significant lower value of RI compared to PR group. We concluded that early image of 99mTc-MIBI SPECT can be helpful in detecting primary lung cancer and metastatic mediastinal lymph node. Additionary, it might be useful for predicting the effects of chemotherapy in small cell lung cancer.

Aged↗
PubMed1997

[Surgical results of emergency coronary artery bypass grafting: effect of left main trunk lesion].

Emergency coronary artery bypass grafting has higher risk than elective surgery. Furthermore, if a lesion is located at left main coronary artery, the frequency of cardiogenic shock or high risk patient would be greater, and operative results would be worse. Between January, 1989 and December, 1995, 45 patients who underwent emergency CABG were included. Age ranged 44 to 80 years (mean 67 +/- 7.6 years; 31 men, 14 women). Of 45 cases, 12 cases were patients with LMT lesion. Results were analysed by univariate analysis and multivariate logistic analysis. Of 45 emergency cases, 5 were operative death and 3 were hospital death. Mortality rate was 17.8%, which was significantly higher than the mortality of elective CABG (2.8%) during the same period (p < 0.001). A factor that influenced the mortality was acute myocardial infarction (AMI), which was confirmed by both univariate and multivariate logistic analyses. Odds ratio (relative risk) was 12.4 for AMI. Only one patient died in 12 cases with LMT (8.3%). This case was due to complication after catheter intervention possibly caused by MOF. Thus, the relative risk of LMT was not so high (p = n.s). Other factors showed no significant correlation. Although the emergency case of LMT lesion was generally severe, we could have the same result as other emergency surgeries when patients were revascularized as soon as possible.

Adult↗
PubMed1997

[Mucosal immune responses against influenza virus].

The respiratory tract-mucosa is the site of either contact with influenza virus or defense against the virus. Such a defense is mediated by immune competent cells. The precursors of IgA-producing B cells and immune T cells are first induced in the mucosal inductive sites such as nasal-associated lymphoid tissues (NALT) or bronchus-associated lymphoid tissues (BALT). They are disseminated to mucosal effector sites for the development of immune responses, where IgA-producing cells in the lamina propria produce polymeric IgA, which are secreted through the epithelial cell into the external. The secretory IgA and serum IgG are mainly involved in protection against influenza in the upper respiratory tract and pneumonia in the lower respiratory tract, respectively. CD8+ cytotoxic T cells and Th1 cells are involved in recovery from influenza.

Animals↗
PubMed1997

[123I-MIBG lung uptake in patients with diabetes mellitus].

The purpose of this study is to clarify the relationship between 123I-MIBG lung uptake and silent myocardial ischemia (SMI), cardiac autonomic neuropathy (AN) or clinical characteristics. For the quantitative analysis, lung to upper mediastinum uptake ratio (L/M) and heart to upper mediastinum uptake ratio (H/M) were obtained from chest planar image. In addition, both lung washout ratio (%WR-L) and heart washout ratio (%WR-H) were calculated from early and delayed images. Each indices were compared in both diabetic and control groups. Mean values of H/M in diabetes with complication were significantly lower than those of control group. Particularly, AN(+)SMI(+) group showed lowest value. Similarly, mean values of %WR-H in diabetes with complication were significantly higher than those of control group and AN(+)SMI(+) group showed highest value. Although mean value of L/M in each diabetic group was significantly higher than that of control group, there was no statistical significance among each diabetes except AN(+)SMI(-) group on early image. Mean value of %WR-L in AN(+) or SMI(+) group was also significantly higher than that of control group, but there was no statistical significance among each diabetic group. The current study suggested that high pulmonary 123I-MIBG uptake in diabetes was independent of the complication of SMI or AN. Pulmonary endothelial dysfunction related with severity of diabetes mellitus was considered to be the most important factor.

3-Iodobenzylguanidine↗
PubMed1997

Comparison of lumen area after PTCA by IVUS and QCA.

The coronary lumen area just after percutaneous transluminal coronary angioplasty (PTCA) was assessed by intravascular ultrasonography (IVUS) with 4.3 F cardiovascular imaging systems (CVIS) and quantitative coronary angiography (QCA) with Kontron CARDIO 500. Altogether 34 lesions were divided into two groups by IVUS findings using Nissen's circular shape factor (CSF), which was defined by the (calculated perimeter/observed perimeter), expressing lumen eccentricity. The eccentric group (CSF < or = 0.92) was 22, and concentric group (CSF > 0.92) was 12. The minimum lumen diameter by IVUS and QCA (both edge-detection and densitometric methods) correlated in both the eccentric and concentric groups. As for the lumen area, only the QCA densitometric method in the concentric group correlated with the lumen area determined by IVUS. Despite using QCA, it is almost impossible for angiography to determine the lumen area just after PTCA if an eccentric lesion with a tear or dissection had occurred.

Aged↗
PubMed1996

Differentiation-dependent enhanced expression of protein phosphatase 2Cbeta in germ cells of mouse seminiferous tubules.

The presence of five distinct isoforms of protein phosphatase 2Cbeta (PP2Cbeta-1 approximately -5) is known. In this study, we demonstrate that the mRNA levels of PP2Cbeta-3, -4 and -5 and PP2Cbeta protein level increased during the course of the first wave of spermatogenesis in neonatal mouse testis. Northern blot and in situ hybridization analyses revealed that PP2Cbeta-3, -4 and -5 were expressed predominantly in pachytene spermatocytes and in more highly differentiated germ cells. The substrate specificity of PP2Cbeta-4 determined with artificial substrates differed from those of PP2Cbeta-3 and -5, suggesting that the difference in the structure of PP2Cbeta-3, -4 and -5 reflect their unique physiological functions in testicular germ cells.

Animals↗